Thermal requirements and population dynamics of root‐knot nematodes on cucumber and yield losses under protected cultivation

Several studies were carried out to determine (i) thermal requirements for development, egg production and emergence of juveniles, and completion of the life cycle of Meloidogyne incognita and Meloidogyne javanica on cucumber, (ii) the maximum multiplication rate and the equilibrium density of root‐knot nematodes on cucumber and yield losses in pot and plastic greenhouse experiments, and (iii) the relationships between relative leaf chlorophyll content (RLCC) and relative cucumber dry top weight biomass (RDTWB) in relation to increasing nematode densities at planting (P_i) in pot experiments. Thermal requirements of M. incognita and M. javanica on cucumber did not differ, irrespective of the biological stage. In the pot experiments, M. javanica completed one generation. The maximum multiplication rate (a) was 833, and the equilibrium density (E) varied according to the effective inoculum densities. The relationship between RDTWB and P_i fitted the Seinhorst damage function model. The RLCC value at 40 or 50 days post‐inoculation also fitted the damage model and was related to RDTWB. In greenhouse experiments, conducted from 2009 to 2012, M. incognita completed three generations. The values for a and E were 1147 and 625 second stage juveniles (J2) per 250 cm³ soil, respectively. The tolerance limit was below zero, and the minimum relative yield ranged from 0·12 to 0·34.     

Effect of abamectin on root-knot nematodes and tomato yield

BACKGROUND: Tomato growers in Shandong Province, China, commonly face heavy root‐knot nematode infestations. Current methods of control include cadusafos and methyl bromide (MeBr), but alternative methods are required because of the high toxicity of these pesticides and the ecological risk of their use. Therefore, abamectin soil applications were evaluated for their potential to control soil nematodes in a series of laboratory tests, greenhouse pot experiments and field trials. RESULTS: Laboratory tests showed that abamectin exhibited rapid knockdown of Meloidogyne incognita, with LC₅₀ and LC₉₀ values that were superior to those of cadusafos and averaged 7.06 and 21.81 mg L^?1. In the greenhouse pot experiment, soil applications of abamectin provided significant M. incognita control similar to that provided by cadusafos while maintaining excellent plant height and vigour. In the field trials, abamectin exhibited excellent control effects to nematodes while giving a higher tomato yield. There was a 19.3–39.0% yield increase from the various treatments compared with the control, and the best results were obtained from the highest dose of abamectin. CONCLUSION: The results of this study demonstrated that abamectin has the potential to be used as an effective alternative to MeBr and cadusafos for nematode control in tomato production in Shandong Province. Copyright © 2012 Society of Chemical Industry     

山东泰安春秋季节大棚番茄根内根结线虫的发育及动态

于2008年秋季和2009年春季对‘毛粉’和‘金丰盛世’2个番茄品种采用网袋法收集根系,酸性品红-次氯酸钠法染色,体视显微镜下检测,记录根内各龄期根结线虫数量和形成的根结数。结果表明,单位鲜根重线虫数量在2008年温度低时,随番茄生长有下降趋势,2009年春季温度升高时则上升,2个供试品种单位鲜根重线虫数无显著差异(P0.05);2008年秋季J2到J3,J3到J4的发育时间均长于2009年,根部形成根结的数量变化趋势相同;当土壤平均温度为15℃时,根结线虫在番茄根内完成第1个世代需32d,25℃时为24d。     

土壤熏蒸结合机械化深耕处理防治连作土壤西瓜根结线虫效果评价

为筛选防治西瓜根结线虫(Meloidogyne incognita)的安全、高效防治技术,本研究对浅耕、深耕、浅耕+棉隆、深耕+棉隆4种土壤连作障碍处理耕作机械化技术防治西瓜根结线虫的效果及对土壤微量元素的影响等进行了评价。结果表明,与对照普通耕作模式相比,4种处理均能显著降低土壤中西瓜根结线虫的数量,提高对根结线虫的防治效果,增加西瓜的产量。其中,以深耕+棉隆处理的防治效果和增产效果最好。深耕+棉隆处理可以增加交换性镁和有效硒的含量,对交换性钙和有效铜的含量没有显著影响。综合评价认为深耕+棉隆处理适于在西瓜根结线虫发生非常严重的地区推广应用,而对于根结线虫发生特别轻的地区,仅以浅耕处理就能有效控制其危害。本研究提供了一种耕作措施与化学农药熏蒸相结合防治根结线虫的新方法,对于减少化肥农药用量,保护农业生态环境安全具有重要意义。     

The influence of continuous cropping and free-living root lesion nematodes on yield of fodder maize

European Journal of Plant Pathology - In field and pot experiments it was investigated, whether continuous cropping of maize causes yield decrease. Although the experiments have not yet enough...     

The long term decline of a population of Avena fatua L., with different cultivations associated with spring barley cropping

The decline of a population of A. fatua established in September 1971, and not allowed to seed thereafter, was monitored in three successive barley crops Numbers of viable seeds in the son in June fell from 159 m² in 1972 to 1 m² in 1974 declining by 83° in the first, and by 96° in the second year. Seedling numbers fell from 138 m² in 1972 to 9 m² in 1974, declining by 32° in their first and by 89° in the second year. The slower decline of seedling numbers in the first year was attributed to loss of dormancy of seed reserves giving proportionally more seedlings in the second spring. Cultivations had no major influence on the pattern of seedling emergence in the spring, but they did affect population level. Where the stubble was cultivated immediately after seeding in September 1971, twice as many seedlings and three times as many seeds in the soil were present in 1972 compared with delayed autumn cultivations in 1971. From this greater reserve of seeds in the soil more seedlings arose in 1973 and in 1974. Time cultivation in the winter of 1971 resulted in slightly more seedlings in 1972 than did ploughing; this greater population declined more rapidly with line cultivation in 1973 and 1974. It is suggested that with no herbicidal control annual line cultivation will lead to a more rapid build up than ploughing: where A. fatua is controlled, the decline should be more rapid with tne cultivation. Persistence of A. fatua as a weed in arable situations seems related more to survivors shedding seeds than to the persistence of seeds on the soil. Factors which may influence the persistence of seeds in the soil are discussed.     

Penetration and reproduction of root-knot nematodes on cucurbit species

Cucurbits are often cultivated in rotation with Solanaceae in double-cropping systems. Most cucurbits have been described as susceptible to root-knot nematodes (RKN) but little is known on their relative levels of susceptibility. Because RKN species differ in rates of root invasion and reproductive traits, isolates of M. arenaria, M. incognita and M. javanica were compared on five cucurbit hosts in experiments run in a climate growth chamber. They included zucchini squash cv Amalthee, cucumber cv Dasher II, melon cv Pistolero, pumpkin cv Totanera and watermelon cv Sugar Baby. All cucurbits were susceptible to the three RKN isolates although M. javanica showed higher invasion rates, faster development and higher egg production than M. arenaria on the selected cucurbits. Apparent differences among cucurbits were primarily due to root invasion rates and formation of egg masses. Both Cucumis species (cucumber and melon) were better hosts for nematode invasion and reproduction than zucchini squash, followed by watermelon. Large invasion rates followed by small reproduction traits were linked to M. incognita on zucchini squash. Reduced invasion rates and egg mass formation along with delayed early development were shown on watermelon.     

Ecological weed management by cover cropping: effects on weed growth in autumn and weed establishment in spring

Cover crops grown in the period between two main crops have potential as an important component of a system‐oriented ecological weed management strategy. In late summer and autumn, the cover crop can suppress growth and seed production of weeds, whereas the incorporation of cover crop residues in spring may reduce or retard weed emergence. Based on these two criteria, six cover crop species were evaluated for their weed suppressive potential in 2 years of experimentation in the Netherlands. Fodder radish, winter oilseed rape and winter rye had the strongest competitive ability in autumn; the competitive strength of Italian ryegrass was intermediate and white lupin and lucerne were poor competitors. Competitiveness was strongly correlated to early light interception. Surprisingly, doubling the recommended sowing density did not increase weed suppressive ability. Although a poor competitor in the fall, after incorporation in spring, lucerne had the strongest inhibitory effect on seedling establishment, followed by winter oilseed rape and white lupin. Winter rye and fodder radish did not affect seedling establishment, whereas Italian ryegrass was not evaluated because of re‐growth after incorporation. Competition in autumn and subsequent residue‐mediated suppression of weed establishment in spring varied among the cover crop species, with winter oilseed rape offering relatively strong effects during both periods.     

不同氮素对根结线虫及土壤微生物的影响

为筛选根结线虫控制技术,采用传统平板法和Biolog ECO生态板评价了液氨、氨水和碳酸氢铵3种氮素对根结线虫及土壤微生物的影响。结果表明,等氮条件下液氨处理杀线虫效果最好且黄瓜产量最高,氨水次之。液氨用量在375.0 kg/hm~2的条件下,对黄瓜根结线虫的防效达到71%,和10%噻唑膦颗粒剂(GF)45.0 kg/hm~2处理相比效果没有显著差异(79.9%)。种植前,细菌数量、AWCD值、Shannon指数、McIntosh指数和Simpson指数均随着液氨用量的增加而减少,随着氨水和碳酸氢铵用量的增加而增加;但所有处理均显著降低了土壤真菌的数量。黄瓜收获后,土壤细菌数量、真菌数量、AWCD值、Shannon指数、McIntosh指数和Simpson指数均随着氮素用量的增加而提高,且高于空白处理和10%噻唑膦GF 45.0 kg/hm~2处理。以上结果说明,液氨、氨水和碳酸氢铵不但可以作为土壤肥料,也可以作为一种高效、低价和生态化的根结线虫防治剂进行推广应用。     

The effect of root-knot nematodes and Ethrel on Fusarium wilt of tomatoes

The reaction of two tomato varieties, Moneymaker (susceptible toFusarium) and Fortos (resistant toFusarium) to inoculation withMeloidogyne javanica, M. incognita andFusarium oxysporum f. sp.lycopersici race1 as well as to application of Ethrel (2 chloroethane phosphonic acid)—an ethylene releasing compound—was studied. With Moneymaker, Ethrel reduced wilt symptoms drastically and this was correlated with a reduction in the number of infected vascular bundles in the stem. Height of the stems was increased. Both nematode species counteracted the therapeutic effect of Ethrel by increasing the number of infected vascular bundles. Fortos remained resistant toFusarium in the presence of nematodes and/or Ethrel. Only, a slight tendency toward resistance-breaking by the nematode was observed. In this variety enhancement of the pathogenic effects of the nematodes by Ethrel was evidenced by increased gall size. Histological studies indicated no difference in xylem structure among the various treatments. These results support the evidence that plant growth regulators play a role in the pathogenicity of root-knot nematodes, theFusarium resistance of the plants, and the effect of nematodes on the severity ofFusarium wilt.Samenvatting Bestudeerd werd de reactie, van twee tomatecultivars, Moneymaker (gevoelig voorFusarium) en Fortos (resistent tegenFusarium) op inoculatie metMeloidogyne javanica, M. incognita enFusarium oxysporum f. sp.lycopersici ras 1, en op behandeling met Ethrel (2 chloorethaan fosfonzuur) een verbinding waaruit ethyleen vrijkomt. Bij Moneymaker resulteerde behandeling met Ethrel in een sterke afneming van verwelkingssymptomen gecorreleerd met een vermindering van metFusarium geinfecteerde vaatbundels in de stengel (Fig. 2 en 3) en een grotere lengte van de planten (Fig. 1). Beide aaltjessoorten hadden het omgekeerde effect en verhoogden het aantal metFusarium geïnfecteerde vaatbundels (Fig. 2 en 3).Bij Fortos was er slechts een zeer geringe mate van verlies van resistentie tegenFusarium onder invloed van de aanwezigheid van wortelknobbelaaltjes. Ethrel elimineerde de geringeFusarium infectie geheel. Bij deze cultivar werd het schadelijk effect van de aaltjes duidelijk versterkt door Ethrel in correlatie, met een sterke toeneming van de omvang der gallen (toeneming wortelgewicht, Fig. 4). Ethrel had geen rechtstreeks effect opFusarium in reincultures.Histologische waarnemingen gaven geen aanwijzingen voor het optreden van veranderingen in de structuur van het xyleem (thyllen) onder invloed, van de behandelingen.De resultaten ondersteunen de opvatting dat groeiregulatoren een rol spelen bij de pathogeniteit van wortelknobbelaaltjes, deFusarium-resistentie van de plant, en de invloed van aaltjes op de ontwikkeling van,Fusarium in de plant.     

不同土壤填加剂及高温闷棚对防治根结线虫病的影响

为明确不同土壤添加剂及高温闷棚技术对防治根结线虫病的影响,2011年在甘肃省白银市进行了试验.结果表明,土壤覆膜+麦草+鸡粪处理5 cm土温显著高于对照约6℃,5 cm土层温度大于40、50℃和60℃的时间分别达18、8和5h,而对照大于40℃持续时间只有9h,且最高温度不超过50℃.从防治效果看,土壤添加麦草、碳酸氢铵、阿维菌素、石灰氮、噻唑膦、阿维·毒死蜱、甘蓝叶和鸡粪等后第一茬防效达100％,第二茬覆膜+麦草+鸡粪也达100％,防效显著,可以在生产中推广应用.     

不同土壤填加剂及高温闷棚对防治根结线虫病的影响

本文比较了室内和田间4种栽培模式:温室大棚、简易大棚+小拱棚、小拱棚、露地条件下黄板、糖醋酒液和清水3种方法对韭菜迟眼蕈蚊成虫的诱集效果,并研究了黄板尺寸、高度、方向对引诱效果的影响.室内试验结果表明,黄板的诱虫效果最好且持效期长,其次是糖醋酒液,清水最差.其中黄板水平放置的诱虫效果好于竖直放置.田间试验结果和室内结果一致,黄板尺寸、高度和数量对引诱效果具有一定的影响,其中390 cm2的黄板诱集效果优于其他尺寸,黄板平放于地面时的诱集效果好于离地面10 cm和20 cm的诱集效果.利用黄板诱杀后对下一代幼虫发生无影响,因此黄板可用于田间监测,不推荐用于防治.     

Smoke pollution and the effects of root-knot nematodes on the growth of eggplants

Single and combined effects of smoke pollution and the root-knot nematode, Meloidogyne incognita race 1, were studied on eggplant in 1988 and 1989 at two sites (K1 and K2) 1 and 2 km respectively away from a coal-fired thermal power plant, and a control site at the Department of Botany, Aligarh Muslim University (AMU). Mean concentrations of SO₂, NO₂ and suspended particulate matter (SPM) were respectively 172, 95 and 626 μg/m³ in 1988 and 144, 97 and 556 μg/m³ in 1989 at K1; and 258, 150 and 344 μg/m³ in 1988 and 226, 113 and 293 μg/m³ in 1989 at K2. Peak levels of the gases and SPM were recorded in the early (12.00–15.00) and late (15.00–18.00) afternoon respectively. Concentrations of the pollutants at a control site were very low. Marginal browning appeared on the leaves of eggplants grown at site K2 whether or not they were infected by the nematodes. The galling caused by nematodes was severe at both polluted sites but egg mass production was inhibited at K2. Egg laying was significantly reduced at both polluted sites. M. incognita significantly reduced plant growth, yield and leaf pigment production of eggplant at the control and polluted sites. Most non-infected plants also showed significant reductions in these plant varieties i.e. from the effects of pollution at K2. Foliar concentrations of sulphur were significantly increased at both polluted sites, being greater in infected plants. The interaction of smoke pollution and M. incognita infection led to greater suppressions at the polluted sites, which were mostly significant at K1. At the polluted sites, leaves had more and longer trichomes; also the number and size of stomata were decreased but their openings were wider especially in infected plants at the two polluted sites.     

Plant‐parasitic nematodes of potential phytosanitary importance,their main hosts and reported yield losses

The potential phytosanitary importance of all named plant‐parasitic nematode species was determined by evaluating available information on species characteristics, association with economically‐important crop hosts, and ability to act as vectors of viruses or form disease complexes with other pathogens. Most named species of plant‐parasitic nematodes (PPN) are poorly known, recorded from a single location only, not associated with economically‐important crops, and not known to be associated with other plant disease organisms. However, 250 species from 43 genera fulfilled one or more of the criteria to be considered to present a phytosanitary risk. The genera and number of species (in parentheses) considered as posing phytosanitary risk included: Achlysiella (1), Anguina (8), Aphasmatylenchus (1), Aphelenchoides (12), Aphelenchus (1), Belonolaimus (2), Bitylenchus (3), Bursaphelenchus (4), Cactodera (3), Ditylenchus (8), Dolichodorus (1), Globodera (3), Helicotylenchus (7), Hemicriconemoides (3), Hemicycliophora (3), Heterodera (25), Hirschmanniella (5), Hoplolaimus (5), Ibipora (3), Longidorus (10), Macroposthonia (2), Meloidogyne (38), Merlinius (3), Nacobbus (1), Neodolichodorus (2), Paralongidorus (2), Paratrichodorus (11), Paratylenchus (3), Pratylenchus (24), Punctodera (3), Quinisulcius (3), Radopholus (5), Rotylenchulus (3), Rotylenchus (1), Scutellonema (5), Sphaeronema (1), Subanguina (3), Trichodorus (5), Tylenchorhynchus (8), Tylenchulus (2), Vittatidera (1), Xiphinema (15) and Zygotylenchus (1). For each of the 250 species main hosts and yield loss estimates are provided with an extensive bibliography. Of the 250 species, only 126 species from 33 genera are currently listed as regulated pests in one or more countries worldwide. Almost all of these 250 species were also associated with economically important crops and some also acted as vectors for viruses.     

生防菌剂与噻唑膦减量配施对番茄根结线虫及根际土壤微生物的影响

减少化学农药的使用, 提高生物农药在田间使用效率对实现化学农药减施及农产品质量安全具有重要意义。本研究以番茄‘新金丰一号’为试验材料, 采用盆栽接种根结线虫的方法研究噻唑膦与生防菌剂以不同剂量配施对番茄根结线虫的防效及对根际土壤微生物的影响。结果表明:噻唑膦减量50%配施50%生防菌剂处理后, 土壤中的根结线虫数量和番茄根系的根结指数相比单独使用噻唑膦或生防菌剂及清水处理均显著降低, 番茄移栽后60 d, 根结线虫减退率为49.61%, 根结指数为32.50, 防治效果达64.77%。与仅用噻唑膦处理相比, 噻唑膦减量50%配施50%生防菌剂处理还显著增加了番茄根际土壤中可培养细菌、放线菌数量及微生物的总量, 其中细菌和放线菌数量较仅用噻唑膦处理增加76.21%和47.96%, 微生物总量增加69.60%。此外, 放线菌门、子囊菌门的相对丰度也显著增加, 而酸杆菌门和芽胞杆菌门的相对丰度则正好相反。无论使用生防菌剂还是噻唑膦减量配施生防菌剂均显著增加了番茄根际土壤中髌骨细菌门、浮霉菌门和木霉属的相对丰度, 但仅使用噻唑膦处理则显著降低了木霉属的相对丰度。综上, 噻唑膦减量50%配施50%生防菌剂可通过增加番茄根际土壤中可培养微生物数量及放线菌门和木霉属等有益微生物的丰度来提高对番茄根结线虫的防效。     

不同栽培模式旱作春玉米农田土壤水分时空动态和产量效应

于2012年和2013年连续两年进行田间定位试验,研究在全膜双垄沟覆盖条件下不同施肥和开花期揭膜处理对春玉米农田土壤水分时空变化特征、土壤含水量和水分利用效率的影响。试验设农户模式(施N 200kg·hm-2,半膜,CK)、高产栽培(施N 380 kg·hm-2,T1)、高产高效栽培(施N 225 kg·hm-2+有机肥,T2)、再高产高效栽培(施N 225 kg·hm-2+有机肥+开花期揭膜,T3)等4个处理,以先玉335为供试玉米品种,分别在玉米各个关键生育期测定土壤含水量,收获测定实际产量。结果表明,T2、T3处理在生育前期、中期不仅能够高效利用浅层(0~100 cm)土壤水分,而且有利于促使深层(100~200 cm)土壤水分向上迁移,为玉米生育后期雨季充分蓄纳降雨腾出库容;从播前到收获0~200 cm土壤贮水量均降低,收获时各处理贮水量依次为CKT1T2T3,差值均小于5 cm,没有显著差异。土壤含水量在0~60 cm土层变化幅度大,而深层(160~200 cm)比较稳定。四种处理间耗水量、产量和水分利用效率存在不同差异,表现为T3T2T1CK。尤其2013年四个处理产量和水分利用效率均达到显著水平,T1、T2、T3产量分别比CK高27.4%、34.8%、42.4%,CK处理水分利用效率比T1、T2、T3分别低21.7%、29.9%、23.7%。高产高效栽培,特别是开花期揭膜的再高产高效栽培模式,在玉米整个生育期不仅没有导致土壤剖面土壤水分显著降低,而且可显著提高籽粒产量和水分利用效率,是该地区值得推广的旱作春玉米栽培模式。     

上海盆景植物寄生线虫种类与群体动态

调查上海地区出口盆景，发现15属植物寄生线虫，其中垫刃线虫、螺旋线虫、环线虫、根结线虫、毛刺线虫、短体线虫、剑线虫、矮化线虫、滑刃线虫等是上海口岸盆景植物主要寄生线虫种类。盆景根围线虫群体密度在1年中的变化与气候变化明显相关。从春到秋，种群数量呈增长趋势，群体结构呈多样化发展，秋天是线虫种群数量、种类最为繁盛时期。     

西南部分地区荞麦根结线虫种类与地理分布

近年来,随着我国荞麦面积的迅速增加,根结线虫病呈逐年加重趋势,严重影响了荞麦的产量与品质。本研究于2014年对西南10个地区17个乡镇秋播苦荞麦根结线虫的分布、发生种类以及危害程度进行了调查。结果表明,西南地区危害荞麦的根结线虫种类有南方根结线虫(Meloidogyne incognita)、爪哇根结线虫(M.javanica)和花生根结线虫(M.arenaria)3种,其中南方根结线虫为优势种群。田间根结线虫种群大多数为单一种群,23.5%的样品为南方根结线虫与爪哇根结线虫(或花生根结线虫)组成的混合种群。调查发现前作为烟草或马铃薯的地块,荞麦根结线虫发生危害严重,平均被害株率为6.0%~77.5%,病情指数为1.4~26.1,而前作为玉米的荞麦根结线虫则较轻,被害株率最高为16.0%,相应病情指数为2.3。